This invention relates to resilient mountings and, in particular, to resilient mountings suitable for use in marine fender assemblies for piers, docks, and the like.
In conventional marine fender assemblies, a fender supported by piles or other means is spaced from and extends along the pier for engagement by a marine vessel. Resilient mountings are disposed between the fender and pier for absorbing the impact energy of the mooring marine vessel. It is desirable to absorb this impact energy at acceptable, relatively low force levels so as not to damage the vessel and/or pier.
Much attention has heretofore been directed at the structure of the resilient mountings. One particular type resilient mounting that has been highly successful is described in U.S. Pat. Re. No. 27,318, assigned to the assignee of the present invention. The resilient mounting there disclosed comprises an elongate body of elastomeric material, such as natural or synthetic rubber which, under axial thrusts of relatively small force, acts as a column under compression and which, under thrusts of greater force, buckles laterally, allowing further deflection without a substantial increase in reaction force until snubbing begins. Buckling takes place in such bodies of elastomeric material when one of the ratio of length to the minimum width or ratio of length to minimum thickness is about two or more. The greater the ratio, the lower the force at which buckling initiates.
Resilient mountings of the foregoing type are particularly suited for marine fender assemblies because of their ability to absorb and dissipate, damp, the large impact energy of a berthing marine vessel at relatively low impact or reaction force levels compared to most other type resilient mountings presently known.
For various reasons, some of which are discussed in the above-referenced patent, it is desirable to control the direction of buckling of such elongate bodies of elastomeric material. In U.S. Pat. Re. No. 27,318, the resilient mounting is contoured to determine the direction of buckling. Such contouring increases the force level at which buckling initiates, constitutes an inefficient use of a portion of the elastomeric material, requires complex and expensive molds for manufacture, and limits the amount of deflection that may take place prior to snubbing.
Another technique for controlling or determining the direction of buckling in elongate bodies of elastomeric material is disclosed in U.S. Pat. Nos. 3,677,017 and 8,803,853. In these patents, support plates, bonded to each end of the elongate body of elastomeric material, include a deflection guide member carried thereby. The deflection guide members cooperate to control the direction of buckling. However, this technique requires modification to or adjacent both of the support plates, and restricts the permissible amount of relative movement of the support plates toward each other. The deflection guide members also create areas of high stress concentration within areas highly stressed in compression adjacent the support plates.